Spatial coherence beams, which propagate from a non-regular grating to a Fraunhofer observation plane, yield spatial coherence Moire patterns. Furthermore, as a result of the analysis of the corresponding interferogram, an effective Moire grating is proposed. In both critical and Kohler's microscope illuminations, Besselian coherence beams propagate between the exit pupil and the exit window of the illumination system. The size of their coherence patches is determined by the field stop of this system.